While some offices may keep food and drink in the fridge, you probbaly don't want to eat anything inside the fridge at the East Middlesex and Suffolk County Mosquito Control Projects office in Waltham. It's full of bags of dead mosquitoes.

As part of the project's mission to determine where spraying should occur and if diseases are being spread, the bugs are collected by field workers in traps, sorted by species in Waltham and eventually tested at a state lab.

Since West Nile virus started appearing in Massachusetts more than a decade ago, along with the more deadly eastern equine encephalitis, what is collected and tested has become a major public health endeavor.

It's difficult to predict how many mosquitoes the area will see this summer, but the spring and early summer mosquito population has been considered normal, said Tim Deschamps, executive director of the Central Massachusetts Mosquito Control Project. The mosquito population for the rest of the season will depend entirely on the weather. The hotter and wetter the weather, the more mosquitoes will thrive, something to consider after last week's extreme heat and heavy rain.

“(The Mosquito Control Projects) do more than we could ever do on our own,” said Jim White, the director of the Natick Board of Health. “They’ll go above and beyond if necessary.”

The goal of these projects is twofold, said David Henley, the superintendent of the East Middlesex and Suffolk County Mosquito Control Projects. It aims to control large mosquito populations and to contain the spread of diseases that affect people and some farm livestock.

“It’s a controlled approach, as opposed to erratically spraying and treating,” said the commissioner of the Central Massachusetts Mosquito Control Project and Milford Board of Health agent Paul Mazzuchelli. “And I think that’s the safest and most effective approach.”

Mosquitoes are caught in one of three types of traps around the state and taken back to the project office. There, an entomologist sorts them by species under a microscope and sends them to the Hinton State Lab Institute in Boston to be tested for disease. The state lab crushes the mass of separated mosquitoes for testing.

Mosquitoes mostly carry two diseases - West Nile virus and eastern equine encephalitis (EEE). There have been no reported cases of either disease this summer, but they tend to appear later in the season, according to Henley. Last year, there was one human case and two animal cases of EEE and eight human cases and two animal cases of West Nile.

Because of its warm winter and spring, 2012 was an especially bad year for these diseases in the Bay State, and by this time two years ago there had been reports of both. In 2012, three people died from EEE and a total of 40 people were sickened with West Nile or EEE.

Page 2 of 2 - Henley explained that this winter and spring were cold so he expects there will be a slow buildup to when the diseases become a risk.

Mosquito control projects, which are funded by member communities, use a number of methods year-round to fight the insects, but ramp up their treatments during the warmer months. If there are any confirmed cases of West Nile or EEE in the area, workers with the control projects increase spraying and add a second round of larvicide treatments.

During the late spring and summer, the groups do ground larvae control in wetlands and catch basins. From the sky, they spray for both larvae and adult mosquitoes. During this time they also catch thousands of mosquitoes and test for diseases. Ditch maintenance takes place year-round and source reduction - reducing the number of places mosquitoes can lay eggs - occurs in every season except summer.

Getting larvicide into where mosquitoes breed falls to workers such as Jon Daigle.

Last week, Daigle biked around Framingham on an unseasonably hot day. The East Middlesex Mosquito Control Project seasonal worker dropped tiny, water-soluble packets of larvacide down storm drains across the town in an attempt to stop mosquitoes before they start.

On the ground, Daigle is part of a six-person crew covering 26 communities this summer, riding mountain bikes along roads, stopping at storm drains and marking each drop with a quick shot of spray paint.

Sometimes the fight goes to the air.

“Airplanes with pesticides would be very effective,” said Henley. “However, environmentally it would come at a cost. Politically it wouldn’t be supported. So we use a variety of lesser measures.”

Aerial spraying was last used over Southeastern Massachusetts because of high levels of EEE being found in mosquitoes.

While West Nile virus often has signs and symptoms similar to the flu and passes within a few days, EEE can be fatal, especially in the very old and very young. EEE signs and symptoms include a high fever, severe headache and almost always results in a prolonged hospital stay. Those who survive the illness often have lingering neurological complications.

There is no vaccine to prevent either illness but health experts say the best way to avoid getting sick is to wear insect repellent, long-sleeved shirts and long pants when outdoors and avoid going outdoors during peak mosquito activity at dawn and dusk.